Studies on the electrochemical impedance spectroscopy of Zr-based Laves phase metal hydride electrodes

The impedance spectra of Zr(V/sub 0.4/Ni/sub 0.6/)/sub 2/, Zr(V/sub 0.2/Mn/sub 0.2/Ni/sub 0.6/)/sub 2/, Zr(V/sub 0.2/Mn/sub 0.2/Ni/sub 0.55/Si/sub 0.05/)/sub 2/ alloys for Ni-MH batteries have been investigated. An equivalent circuit for the reaction of an MH electrode is proposed. The results reveal that: (1) the additions of Mn and Si have significant effects on the reaction resistances of the alloys; (2) Ni powder is an appropriate additive material in the manufacturing process of an MH electrode; and (3) the amounts of Ni powder in the alloy electrode also should be considered in the practical utilisation.